<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      Object.prototype.say = function () {
        console.log("hello");
      };
      // Array.prototype.say = function () {
      //   console.log("hello");
      // };
      // Array.prototype.join = function () {
      //   console.log("hello");
      // };
      // String.prototype.say = function () {
      //   console.log("hello");
      // };
      const obj1 = {};
      const obj2 = {};
      const arr1 = [];
      const arr2 = [];
      const str1 = "";
      const str2 = "";

      str1.say(); //hello
      arr1.say(); //hello
      Date.prototype.say();
    </script>
  </body>
</html>
